I usually just sieve compost over them so they have a lightweight covering. Some don't need it as they need light to help germination.

it looks smart but I don't know if it is essential. A dear friend reckons its a ploy to get us to buy it and therefore spend money on stuff we don't really need. After all that isn't what happens in nature. I am inclined to agree.

Some very fine seeds do better if sown on fine grit and then 'pulled' into the compost by soaking the pot rather than overhead watering.
Some people use Vermiculite over the seeds, I find that I get no germination at all if I do.
The grit is supposed to stop liverwort and moss, it don't. Watering with tap water not rainwater helps with that.
Personal choice really, do what ever works for you.

Yes I sometimes cover my seeds with grit or vermiculite to keep liverwort at bay ... but not always. A personal choice, and not essential.

For a plant in a pot outside, stones certainly keep the squirrels away!

I've always just lightly sprinkled compost over the top, the sprinkling with grit seems quite a recent innovation, I can't recall Percy Thrower doing it but that could be my memory mucking about

I can see why in a commercial world it may help, looks nice and helps sell, but for me it would be just an extra that serves no real purpose

Thank you for your replies. Yes, might look nice and not really necessary, so its a fine coating of compost will be used by me. :)

I don't do well with Vermiculite either, Owd. I shall stick with a fine layer of compost.

I don't rate the CK programme much though nobody can say she isn't enthusiastic!

I really enjoy her programme. The grit looks smart and helps keep moisture in, I find it helps against fungal disease too